Developing Porphyra/salmon integrated aquaculture for bioremediation and diversification of the aquaculture industry

For rapid growth and appropriate pigmentation, Porphyra requires the constant availability of nutrients, especially in summer when temperate waters are generally nutrient depleted. Cultivation near salmon cages allows the alleviation of this seasonal depletion by using the significant loading of fish farms, which is then valued (wastes become fertilisers) and managed (competition for nutrients between desirable algal crops and problem species associated with severe disturbances). Porphyra, being an extremely efficient nutrient pump, is an excellent candidate for integrated aquaculture for bioremediation and economic diversification. Frequent harvesting provides for constant removal of significant quantities of nutrients from coastal waters, and for production of seaweeds of commercial value. The production of P. yezoensis being limited in the Gulf of Maine, an assessment of the potential of seven native north-west Atlantic Porphyra species is presently in progress. To enable the production of conchospores for net seeding, the phenology of these species and the conditions for their vegetative conchocelis exponential growth, conchosporangium induction, and conchospore maturation were determined. The development of integrated aquaculture systems is a positive initiative for optimising the efficiency of aquaculture operations, while maintaining the health of coastal waters.